vellum-migration-checklist

# Vellum Migration Checklist ## When A Migration Is Required Use a migration for shipped interfaces and persisted data: - DB schema changes, indexes, backfills, or persisted row shape changes. - Workspace file renames, moves, format changes, or namespace changes. - Stored config or data that existing installs must keep reading. Do not delete migration files. Migrations are append-only, even when their logic becomes obsolete. ## DB Migrations For DB migrations: 1. Add a new file under `assistant/src/persistence/migrations/`. 2. Make it idempotent and safe to retry after interruption. 3. Register it in the `migrationSteps` array in `assistant/src/persistence/steps.ts`. 4. Update schema modules if the runtime schema changed. 5. Add or update a focused `db-*migration*.test.ts` test. Check for ordering drift and never reorder existing migrations. ## Workspace Migrations For workspace migrations: 1. Add a new numbered file under `assistant/src/workspace/migrations/`. 2. Append it to `WORKSPACE_MIGRATIONS` in `assistant/src/workspace/migrations/registry.ts`. 3. Make the migration idempotent. 4. Add or update a focused `workspace-migration-*.test.ts` test. Never reuse or reorder existing migration IDs. ## Release Notes Migrations There is currently no release-note surfacing mechanism. The update-bulletin feature (workspace migrations appending to a workspace bulletin file, processed by a background conversation at daemon startup) was removed. Do not add new `0XX-release...